JP2006221062A - Method of manufacturing lamination type diffraction optical element and lamination type diffraction optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a lamination type diffraction optical element by which firm joint is attained and a joining process is made efficient to be able to drastically reduce the cost in a joining technique for forming the lamination type diffraction optical element by laminating a pair of diffraction optical elements formed by a replica forming method. <P>SOLUTION: In the replica forming process of the diffraction optical element, a joint part of one of the diffraction optical element is formed and a photosetting resin uncured part of another one of the diffraction optical element to make a pair is formed. In the joint step for forming the lamination type diffraction optical element by laminating a pair of the the diffraction optical elements formed in the replica forming process, the joint part of the diffraction optical element and the photosetting type resin uncured part are joined and irradiated with light for curing. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing an optical element and an optical element, and more particularly to a method for manufacturing a laminated diffractive optical element by so-called replica molding, which obtains a desired optical surface shape by transferring a molding surface to a photocurable resin by a molding die, and The present invention relates to a laminated diffractive optical element, a method for producing a laminated diffractive optical element formed by bonding the diffractive optical element, and the laminated diffractive optical element.

  Conventionally, as one of the molding techniques for optical elements such as diffractive optical elements and aspherical lenses, it is characterized by excellent large area moldability and high transferability, and replica molding that is suitable for mass production due to the ease of the molding technique There is technology. In this replica molding technique, a photocurable resin is dropped onto a mold surface having a reversal shape of a desired optical shape, and a lens blank is crimped and spread out from the mold surface. The light curable resin is irradiated to cure the photocurable resin, and the cured resin is released from the mold together with the lens blank.

  Furthermore, there is a joining technique in which a pair of diffractive optical elements molded by the replica molding technique are bonded together to form a laminated diffractive optical element in order to add small and high-performance optical performance.

  For example, as shown in FIG. 1, when the paired diffractive optical elements 1 and 2 are bonded to each other, a plane part 3 is provided on the outer periphery of the outer end of the optical effective diameter of each diffractive optical element. The laminated diffractive optical element 4 is formed by sticking the parts together and positioning with high accuracy and fixing them with an adhesive. The shape of the flat surface portion 3 is formed simultaneously with the optically effective surface by transferring the inverted shape of the flat surface portion installed on the outer peripheral portion of the forming die in replica forming.

  In the replica molding method for molding a diffractive optical element and an aspherical lens, many methods for molding a desired optical shape and a mechanism shape such as the above-described flat portion 3 with high accuracy have been proposed.

  As a precedent proposal for the subject of the present invention, in Patent Document 1, after photocurable resin is filled to the outside of a desired optical effective area, photocuring is performed through a mask that shields the outside of the optical effective area. There has been proposed a method for improving the transferability of the optically effective area by irradiating a light-sensitive resin with light.

  Furthermore, in a joining technique for forming a laminated diffractive optical element by bonding together a pair of diffractive optical elements formed by the replica molding method, several methods for highly accurately, firmly and efficiently joining have been proposed. Yes.

As a precedent proposal for the subject of the present invention, in Patent Document 2, an adhesive is applied to the outer peripheral portion outside the optical effective diameter of the diffractive optical elements to be bonded to each other, and this is cured to be highly accurate and strong. A method of joining has been proposed.
JP-A-6-75106 JP 2002-182022 A

  In a joining technology that forms a laminated diffractive optical element by bonding together a pair of diffractive optical elements molded by the replica molding method, high-precision positioning and strong bonding, and further improvement in the efficiency of the joining process are required. It has been. Normally, the central axes of the two diffractive optical elements are positioned with an accuracy of less than ± 2 μm, but if this position deviates by more than ± 2 μm, a ripple occurs in the diffraction efficiency representing the optical performance. The optical performance of the device is significantly reduced. In addition, when the bonding of two diffractive optical elements is not strong due to poor adhesion or the like, the laminated diffractive optical element is easily broken by environmental fluctuations such as temperature and humidity and small external impacts.

  However, in Patent Document 1, an uncured resin portion is formed outside the optically effective region by irradiating light to the photocurable resin through a mask that shields the outside of the optically effective region. Since the cured resin portion does not contribute to the bonding process at the time of bonding of the optical element, the diffractive optical element cannot be bonded firmly.

  Furthermore, in Patent Document 2, two diffractive optical elements are bonded to each other with high accuracy and firmly by applying an adhesive to the outer peripheral portion outside the optical effective diameter of the diffractive optical elements to be bonded to each other and curing the adhesive. The joining process cannot be made more efficient for the following reasons.

  More specifically, the bonding process in Patent Document 2 includes a step of bonding flat portions installed outside the effective optical diameter of each diffractive optical element to each other and positioning with high accuracy, and a pair of positioned diffractive optical elements. Is composed of a step of fixing with an adhesive. The step of attaching the flat portions installed outside the effective optical diameter of the diffractive optical element to each other with high accuracy can be efficiently performed by using an image processing technique for recognizing the position and a precision driving technique for controlling the position. it can. However, in the process of fixing the pair of positioned diffractive optical elements with an adhesive, a small amount of adhesive such as a photo-curing resin is precisely applied to three or more points on the outer periphery of the diffractive optical element using an adhesive application device. Since it must be applied, it takes a long time and reduces the production efficiency. Furthermore, the use of the adhesive and the adhesive applicator and the deterioration of the yield due to the failure of the adhesive application lead to an increase in the cost of the product.

  Therefore, in view of the above problems, the present invention is a bonding technique for forming a laminated diffractive optical element by bonding a pair of diffractive optical elements molded by a replica molding method to each other, which is stronger than the conventional technique. It is an object of the present invention to provide a method for manufacturing a laminated diffractive optical element and a laminated diffractive optical element, which can achieve simple joining and can improve the efficiency of the joining process and greatly reduce costs.

  The invention of claim 1 for solving the above-mentioned problems is a method in which a photocurable resin is dropped on a mold surface having a desired optical shape, and the photocurable resin is pressed and filled with a flat or curved glass substrate. Manufacture of a laminated diffractive optical element by forming a diffractive optical element by releasing a molded product composed of the photocurable resin and a glass substrate after light irradiation, and joining the paired diffractive optical element In the method, a step of forming a joint portion of one diffractive optical element, a step of forming a photocurable resin uncured portion of the other diffractive optical element to be paired, a joint portion of the diffractive optical element, and the light A method of manufacturing a laminated diffractive optical element, comprising: a step of bonding a curable resin uncured portion; and a step of irradiating light to the bonded portion and the photocurable resin uncured portion. .

  In the above configuration, in the step of forming the joint portion of one diffractive optical element, a shape for joining is formed outside the optically effective one diffractive optical element, and the photo-curing property of the other diffractive optical element that forms a pair is formed. In the step of forming the resin uncured portion, the photocurable resin uncured portion is formed at a position that matches the shape for joining of the other diffractive optical element described above of the other diffractive optical element to be paired. In the step of joining the joint portion of the optical element and the uncured portion of the photocurable resin, the shape for joining in the one diffractive optical element described above and the uncured portion of the photocurable resin of the other diffractive optical element are Are joined to each other, and in the step of irradiating light to the joint and the uncured portion of the photocurable resin, the photocurable resin is irradiated with light to the joint shape described above. By curing the uncured part, Like the diffractive optical element to form a anchored laminated diffractive optical element.

  According to a second aspect of the present invention, there is provided a method for producing a laminated diffractive optical element, wherein the diffractive optical element is molded on a molding die surface of the diffractive optical element using a molding die having an inverted shape of the joint portion. It is.

  In the above configuration, the diffractive optical element is molded using a mold having a reversal shape of the joining portion on the mold surface of the diffractive optical element, and the optical shape of the diffractive optical element and the shape for bonding are simultaneously formed. To do.

  According to a third aspect of the present invention, a light-shielding mask is disposed between the formation portion of the uncured portion of the photocurable resin and the light source for photocuring, and the diffractive optical element is irradiated with light through the light-shielding mask. This is a method for producing a laminated diffractive optical element.

  In the above configuration, a light-shielding mask is disposed between the light-curing resin uncured portion forming portion and the light-curing light source, and the diffractive optical element is irradiated with light through the light-shielding mask. The optical shape of the element and a photo-curing resin uncured portion for bonding are simultaneously formed.

  A fourth aspect of the present invention is a laminated diffractive optical element manufactured using the manufacturing method according to any one of the first, second, and third aspects.

  As described above, according to the first invention of the present application, in the joining technique for forming a laminated diffractive optical element by bonding a pair of diffractive optical elements molded by a replica molding method to each other, Compared to the above, a strong bond can be obtained, and the efficiency of the bonding process and a significant cost reduction can be achieved.

  Further, according to the second invention of the present application, the optical shape of the diffractive optical element and the shape for bonding can be formed at the same time, so that the efficiency of the further bonding process and the cost can be significantly reduced.

  Further, according to the third invention of the present application, the optical shape of the diffractive optical element and the uncured portion of the photocurable resin for bonding can be formed at the same time, which further increases the efficiency of the bonding process and significantly reduces the cost. It becomes possible.

  Further, according to the fourth invention of the present application, the entire optical system can be reduced in size and weight as compared with a conventional optical system using an aspheric lens, fluorite, or the like, and optical chromatic aberration can be satisfactorily achieved. Can be corrected.

  Hereinafter, as an embodiment of the present invention, replica molding of a diffractive optical element using a photocurable resin, and a bonding step of forming a laminated diffractive optical element by bonding a pair of diffractive optical elements molded by the replica molding Will be described.

  FIG. 2 is a schematic block diagram showing a diffractive optical element replica molding apparatus used for the camera lens according to the first embodiment of the present invention. In FIG. 2, 5 is a molding die in which a reverse shape 6 of the desired optical function shape and a shape 7 of the joint portion are provided on the molding surface. The molding die 5 is fixed, and the lens blank 9 is placed on the ring-shaped lens blank holding member 8 into which the molding die 5 is fitted. Axis alignment between the center axis of the lens blank 9 and the center of the molding surface of the molding die 5 is performed by molding the molding die 5 on the entire circumference of the inner peripheral portion on which the lens blank 9 on the lens blank holding material 8 is placed. This is realized by providing a fitting portion having a depth of 1 mm and a width of about 1 mm, the center of which is aligned with the axis, and fitting the outer peripheral portion of the lens blank 9 into the fitting portion. The lens blank 9 is made of glass or plastic material, and has a flat surface or a curved surface on the optical surface. The ring-shaped lens blank holding member 8 is held so as to be movable up and down. An appropriate amount of a photo-curable resin 10 is supplied onto the molding surface of the molding die 5 by a dispenser (not shown), and an ultraviolet irradiation lamp 11 is disposed above the lens blank 9 with respect to the optical function surface of the molding die 5. Are installed so that they are perpendicularly incident. As the photocurable resin 10, an optical resin such as an acrylate, methacrylate, or epoxy that generates radicals from absorption of a photoinitiator near an ultraviolet wavelength of 365 nm is used. A light source having an oscillation peak in the vicinity of a wavelength of 365 nm of a lamp or an ultrahigh pressure mercury lamp is used.

  FIG. 8 is a schematic block diagram showing a diffractive optical element replica molding apparatus used in the camera lens according to the first embodiment of the present invention. In FIG. 8, reference numeral 18 denotes a molding die provided with a reverse shape 6 of a desired optical function shape on its molding surface. The molding die 18 is fixed, and the lens blank 9 is placed on the ring-shaped lens blank holding member 8 into which the molding die 18 is fitted. Axis alignment between the center axis of the lens blank 9 and the center of the molding surface of the molding die 18 is performed by molding the molding die 18 on the entire circumference of the inner peripheral portion on which the lens blank 9 on the lens blank holding material 8 is placed. This is realized by providing a fitting portion having a depth of 1 mm and a width of about 1 mm, the center of which is aligned with the axis, and fitting the outer peripheral portion of the lens blank 9 into the fitting portion. The lens blank 9 is made of glass or plastic material, and has a flat surface or a curved surface on the optical surface. The ring-shaped lens blank holding member 8 is held so as to be movable up and down. An appropriate amount of photocurable resin 10 is supplied onto the molding surface of the molding die 18 by a dispenser (not shown), and a ring-shaped shading mask 19 is installed on the lens blank 9, and above the lens blank 9. The ultraviolet irradiation lamp 11 is installed so that the ultraviolet light is perpendicularly incident on the optical functional surface of the molding die 18. As the photocurable resin 10, an optical resin such as an acrylate type, a methacrylate type, or an epoxy that generates radicals from absorption of a photoinitiator near an ultraviolet wavelength of 365 nm is used. A light source having an oscillation peak in the vicinity of a wavelength of 365 nm of a lamp or an ultrahigh pressure mercury lamp is used.

  FIG. 3 shows a top view and a side view of the molding die 5 in this embodiment. The fine shape forming the optical function surface 6 has a blazed diffraction grating having a grating height of 5 to 20 μm and a grating width of 0.1 to 3 mm on a plane at an effective optical diameter of φ20 mm, as shown in the top view. Concentric with a convex shape toward the center. The joint shape 7 is concentrically arranged in a wedge-shaped groove shape having a height of 30 to 200 μm and a width of 0.1 to 1 mm outside the optical effective diameter. The fine shape of the molding surface is formed by a die plating layer cutting method or the like.

  FIG. 9 shows a top view and a side view of the molding die 18 in this embodiment. The fine shape forming the optical function surface 6 has a blazed diffraction grating having a grating height of 5 to 20 μm and a grating width of 0.1 to 3 mm on a plane at an effective optical diameter of φ20 mm, as shown in the top view. Concentric with a concave shape toward the center. The fine shape of the molding surface is formed by a die plating layer cutting method or the like.

  FIG. 4 shows a diffractive optical element 12 ideally produced by the molding die 5 in this embodiment. The optical functional surface 6 ′ of the resin layer formed on the lens blank 9 is formed concentrically as a concave shape toward the center of the blazed diffraction grating, that is, as an inverted shape of the molding die 5. Similarly, the shape 7 ′ of the joint portion of the resin layer is formed concentrically as an inverted shape of the shape 7 of the joint portion in the molding die 5.

  FIG. 10 shows a diffractive optical element 20 ideally produced by the molding die 18 in this embodiment. The optical functional surface 6 ′ of the resin layer formed on the lens blank 9 is formed concentrically as a convex shape toward the center of the blazed diffraction grating, that is, as an inverted shape of the molding die 18. 17 is an uncured portion of the photocurable resin formed in the molding process of this example, and is formed concentrically with a width of 0.1 to 1 mm outside the effective optical diameter.

  FIG. 5 is a schematic configuration diagram illustrating a diffractive optical element bonding and bonding apparatus according to the present embodiment. A diffractive optical element holding member 13 is provided with a vacuum system mechanism for holding the lower surface of one diffractive optical element 12 disposed below by vacuum suction. Reference numeral 14 denotes a center axis alignment mechanism of a diffractive optical element provided with a piezoelectric element, and is arranged so that the lens blank side surface of the other diffractive optical element 20 placed thereon can be pressed from at least two directions. The optical microscope 15 is installed above the diffractive optical element and is adjusted so as to focus on the shape part of the diffraction grating of the diffractive optical element, but it is desirable that the depth of focus is as deep as possible for the convenience of work. Reference numeral 16 denotes an ultraviolet irradiation lamp, which uses a light source having an oscillation peak in the vicinity of a wavelength of 365 nm of a high pressure mercury lamp or an ultrahigh pressure mercury lamp. Reference numerals 7 ′ and 17 respectively denote the shape of the joint in the diffractive optical element 12 and the uncured portion of the photocurable resin in the diffractive optical element 20.

  Next, the molding process of the diffractive optical element 12 in the present embodiment will be described with reference to FIGS. First, an appropriate amount of a photocurable resin 10 is supplied to the vicinity of the center of the molding surface of the molding die 5 by a dispenser (not shown), and a lens blank is previously subjected to silane coupling treatment for increasing the adhesion to the resin on one side. 9 is fitted into a fitting portion provided on the inner periphery of the ring-shaped lens blank holding member 8 with the coupling processing surface facing down. At this time, a mechanism for holding the lens blank 9, such as a centering chuck or a bell clamp system, may be provided.

  Next, as shown in FIG. 6, the ring-shaped lens blank holding member 8 is lowered, the molding die 5 and the lens blank 9 are relatively approached, and the photocurable resin 10 is made to have a desired thickness and optical properties. Push to fill the outer circumference of the effective diameter. At this time, the liquid contact speed is adjusted in consideration of the viscosity of the resin and the wettability of the molding surface of the mold in order to prevent air bubbles from being mixed into the photocurable resin 10 and unfilled resin in the molded shape of the mold. There must be.

Next, the filled photocurable resin 10 is irradiated with ultraviolet light from the ultraviolet irradiation lamp 11 for 24 J (40 [mW / cm ² ] × 10 minutes). After completion of the polymerization and curing of the photocurable resin 10, the ring-shaped lens blank holding member 8 is lifted so that the diffractive optical element 12 composed of the photocurable resin 10 cured from the molding die 5 and the lens blank 9. To peel off.

  Next, the molding process of the diffractive optical element 20 in the present embodiment will be described with reference to FIGS. First, an appropriate amount of the photocurable resin 10 is supplied to the vicinity of the center of the molding surface of the molding die 18 by a dispenser (not shown), and a silane coupling process is performed on one side in advance to increase the adhesion with the resin. 9 is fitted into a fitting portion provided on the inner periphery of the ring-shaped lens blank holding member 8 with the coupling processing surface facing down. At this time, a mechanism for holding the lens blank 9, such as a centering chuck or a bell clamp system, may be provided.

  Next, as shown in FIG. 7, the ring-shaped lens blank holding member 8 is lowered, the molding die 18 and the lens blank 9 are relatively approached, and the photocurable resin 10 is made to have a desired thickness and optical properties. Push to fill the outer circumference of the effective diameter. At this time, the liquid contact speed is adjusted in consideration of the viscosity of the resin and the wettability of the molding surface of the mold in order to prevent air bubbles from being mixed into the photocurable resin 10 and unfilled resin in the molded shape of the mold. There must be.

Next, ultraviolet light from the ultraviolet irradiation lamp 11 is applied to the filled photocurable resin 10 through a ring-shaped light shielding mask 19 disposed outside the optical effective diameter on the lens blank 9 by 18J (100 [100 [ mW / cm ² ] × 3 minutes). At this time, since the resin portion shielded by the ring-shaped shading mask 19 of the photocurable resin 10 is not cured, the photocurable resin uncured portion 17 is formed. After the light irradiation is completed, the ring-shaped lens blank holding member 8 is lifted, so that the diffractive optical element composed of the photocurable resin 10 including the photocurable resin uncured portion 17 and the lens blank 9 is formed from the molding die 18. The element 20 is peeled off.

  Next, the bonding process of the diffractive optical element in this embodiment will be described with reference to FIG. The diffractive optical element 12 obtained from the replica molding step described above is fitted into the diffractive optical element holding member 13, and the vacuum system mechanism provided in the diffractive optical element holding member 13 is activated to hold the diffractive optical element 12 by suction. The diffractive optical element 20 forming a pair is placed on the diffractive optical element 12. At this time, the joint shape 7 ′ is inserted into the uncured portion 17 of the photocurable resin and placed. The order of placing the diffractive optical element 12 and the diffractive optical element 20 may be reversed.

Next, accurate positioning is performed by the center axis alignment mechanism 14 of the diffractive optical element including the piezoelectric element while constantly confirming the bonding position using the optical microscope 15. Further, ultraviolet light from the ultraviolet irradiation lamp 16 is irradiated to the uncured portion 17 of the positioned diffractive optical element 20 by 18 J (100 [mW / cm ² ] × 3 minutes). At this time, since the uncured portion 17 of the photocurable resin is cured, the uncured portion 17 of the photocurable resin 17 and the shape 7 'of the bonded portion are fixed, so that the laminated diffraction in which a pair of diffractive optical elements are bonded. An optical element is formed.

  As described above, according to the present embodiment, compared to the conventional one, a strong bonding can be obtained because the bonding is performed by the molding photo-curing resin itself without using an adhesive. Moreover, since an adhesive and an adhesive application device are not required, the efficiency of the joining process and a significant cost reduction can be achieved. In addition, it is possible to configure an optical system using such an excellent laminated diffractive optical element and to apply them to an imaging apparatus or an observation apparatus.

It is sectional drawing and a top view explaining the multilayer type diffractive optical element of a prior art example. It is sectional drawing of the shaping | molding die and shaping | molding apparatus which show embodiment of this invention. It is sectional drawing and the top view of the molding die which show embodiment of this invention. It is sectional drawing and the top view of the diffractive optical element which show embodiment of this invention. It is sectional drawing of the joining apparatus and diffractive optical element which show embodiment of this invention. It is sectional drawing of the shaping | molding die and shaping | molding apparatus which show embodiment of this invention. It is sectional drawing of the shaping | molding die and shaping | molding apparatus which show embodiment of this invention. It is sectional drawing of the shaping | molding die and shaping | molding apparatus which show embodiment of this invention. It is sectional drawing and the top view of the molding die which show embodiment of this invention. It is sectional drawing and the top view of the diffractive optical element which show embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Diffractive optical element 2 Diffractive optical element 3 Flat part of outer periphery of optical effective diameter outer peripheral part 4 Laminated diffractive optical element 5 Mold 6 Optical function shape 6 'Optical function shape 7 Joint shape 7' Joint shape 8 Lens blank holding member 9 Lens blank 10 Photocurable resin 11 Ultraviolet irradiation lamp 12 Diffractive optical element 13 Diffractive optical element holding member 14 Center axis alignment mechanism 15 of diffractive optical element 15 Optical microscope 16 Ultraviolet irradiation lamp 17 Photocurable resin uncured portion 18 Molding die 19 Ring-shaped light shielding mask 20 Diffractive optical element

Claims (4)

  A photocurable resin is dropped on a molding die surface having a desired optical shape, the photocurable resin is pressed and filled with a flat or curved glass substrate, and after the light irradiation, the molding comprising the photocurable resin and the glass substrate is performed. Forming a junction part of one diffractive optical element in a manufacturing method in which a diffractive optical element is formed by releasing a product and a laminated diffractive optical element is manufactured by joining the paired diffractive optical elements And a step of forming a photocurable resin uncured portion of the other diffractive optical element to be paired, a step of bonding the bonded portion of the diffractive optical element and the uncured portion of the photocurable resin, and the bonding And a step of irradiating light to the uncured portion of the photocurable resin and a method for producing a laminated diffractive optical element.   The step of forming the joint portion of the diffractive optical element comprises forming the diffractive optical element using a mold having a reversal shape of the joint portion on the mold surface of the diffractive optical element. A method for manufacturing a diffractive optical element.   The step of forming the light curable resin uncured portion of the diffractive optical element includes disposing a light shielding mask between the light curable resin uncured portion forming portion and the light curing light source, and the light shielding mask. A method for producing a laminated diffractive optical element, wherein the diffractive optical element is irradiated with light through   A laminated diffractive optical element manufactured using the manufacturing method according to claim 1, 2 or 3.

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